feat: add dedicated douyin workbench entry

scripts/start_douyin_workbench.sh

@@ -0,0 +1,35 @@
+#!/bin/sh
+set -eu
+
+ROOT="$(CDPATH= cd -- "$(dirname "$0")/.." && pwd)"
+PORT="${DOUYIN_WORKBENCH_PORT:-3618}"
+SCRIPT="$ROOT/scripts/douyin-browser-capture/control_panel.mjs"
+LOG_FILE="${DOUYIN_WORKBENCH_LOG:-/tmp/storyforge-douyin-workbench.log}"
+
+if lsof -nP -iTCP:"$PORT" -sTCP:LISTEN >/dev/null 2>&1; then
+  echo "douyin workbench already running: http://127.0.0.1:$PORT/workbench"
+  exit 0
+fi
+
+nohup env PORT="$PORT" node "$SCRIPT" >"$LOG_FILE" 2>&1 &
+
+python3 - <<'PY'
+import os
+import time
+import urllib.request
+
+port = os.environ.get("PORT", "3618")
+url = f"http://127.0.0.1:{port}/workbench"
+deadline = time.time() + 15
+last_error = ""
+while time.time() < deadline:
+    try:
+        with urllib.request.urlopen(url, timeout=3) as resp:
+            print(f"douyin workbench ready: {resp.status} {url}")
+            raise SystemExit(0)
+    except Exception as exc:
+        last_error = str(exc)
+        time.sleep(0.5)
+print(f"douyin workbench start timeout: {last_error}")
+raise SystemExit(1)
+PY